The causes and consequences of the contrasting patterns of migration are important and remain essentially unexplored. Those who regard themselves as sojourners in the city will seek different kinds of housing demand fewer amenities and services behave differently with respect to making friends and joining organizations use accumulated savings for different purposes and respond to different political issues and candidates than will people committed to the city as their permanent home. Where a large proportion of inmigrants regard their stay as temporary patterns of informal and formal urban social organization the nature and degree of demands on urban government and even the physical development of the city will be affected. This will hold regardless of whether the migrants who expect to return to their home places in fact do so. As long as they plan to return their intentions will shape their behavior in the city. Attention in this comparison of sojourners and new urbanites is directed to the following: variation in the permanence of cityward migration (intercountry differences the long run trend toward permanence); causes of variation in the permanence of cityward migration (economic and social consequences levels and patterns of political participation migration patterns and national political dynamics). Clearly the stability of demand for urban labor partly determines the mix of temporary and permanent migrants. Differences in levels of industrialization and the pace of economic growth must account for much of the contrast in migration patterns between South Asia and Africa on the 1 hand and Latin America Taiwan and Korea on the other. Tensions among ethnic groups are a less noted urban factor which may affect the permanence of migration. Urban conditions in general or as they bear on specific groups are only part of the explanation for varying migration patterns. For example except where strong economic discrimination is involved urban economic conditions fail to explain the behavior of atypical streams--temporary or cyclic migrants in places where permanent migration is the norm or permanent migrants in heavily temporary settings. Rural migrants desire and ability to return home after a shorter or longer stay in the city are strongly affected by their access to the land or to alternative sources of rural livelihood by rural kinship structure the importance of age graded social roles the cultural and religious significance of the land and by customs or events which make outcasts of certain groups of people. Rural conditions probably are the most important explanation for the particular forms of temporary migration in different areas but for the behavior of atypical streams. Commitment to the city strongly influences the flow of private savings into urban housing and associated amenities.